Assume that the ends of the bar in have been kept at 100°C for a long time. Then at some instant, call it t 0, the temperature at x Lis suddenly changed to 0°C and kept at 0°C, whereas the temperature at x 0 is kept at 100°C. Find the temperature in the middle of the bar att 1, 2, 3, 10, 50 sec First guess, then calculate.

Awall of 0.5m thickness is to be constructed from a material which has average thermal conductivity of 1.4 w/mk. the wall is to be insulated with a material having an average thermal conductivity of 0.35 w/mk so that heat loss per square meter shall not exceed 1450 w. assume inner wall surface temperature of 1200°c and outer surface temperature of the insulation to be 15°c. calculate the thickness of insulation required.